The separation of isotopes in the gas phase and, especially, uranium isotopes for uranium enrichment, based upon different molecular weights, different kinetic cross sections of the molecules of the isotopes to be separated in the gas phase, or like differences in physical properties of the gaseous compounds of the two isotopes, can be effected by a separating-nozzle process well documented in the literature and described, inter alia, in the aforementioned copending applications and patent, the publications mentioned in the specifications thereof, and in the references applied or made of record therein including, for example, German Pat. Nos. 1,052,955, 1,091,541, 1,794,174 and 2,542,296 and the German application No. P 27 41 461 corresponding to application Ser. No. 928,436. Attention may also be directed to the references cited in these cases.
In the separating-nozzle process, the gas mixture, e.g. uranium hexafluoride containing uranium isotopes to be separated, is forced with or without a carrier (e.g. low molecular weight gas) through slit-like nozzles, the outflow of which is intercepted by skimmer-diaphragm arrangements defining an opening between the two skimmers. The molecules of the higher isotope preferentially pass into the opening while the molecules of lower molecular weight component of the mixture tend to bypass the opening as a result of the outward diffusion of these molecules in the jet.
Apart from the references mentioned above, separating-nozzle systems, their structural and operating principles and the compressors and like auxiliary devices used with them can be found in U.S. Pat. No. 3,362,131, U.S. Pat. No. 3,708,964, U.S. Pat. No. 3,877,892, German Pat. No. 2,031,678 and publications:
Chemie-Ingenieur-Technik, Vol. 29, p. 364 ff. (1957); PA1 Chemie Ingenieur Technik, Vol. 39, p. 1 ff. (1967); PA1 Atomwirtschaft/Atemtechnik, Vol. 13, p. 359 ff. (1968).
In applicant's early work in this field, in part described in the above-mentioned applications and publications, efforts were made to provide compact systems for carrying out separating-nozzle process in cascade so as to maximize isotope separation.
In general, the earlier apparatuses from which the present developments derive, had a cylindrical housing or vessel, separating-nozzle units connected in a separating cascade resulting in a gradual enrichment of at least one component of the gas mixture in at least one of the uranium isotopes, respective coolers associated with the separating-nozzle units, e.g. compression heat and compressor aggregates which provided at least one compressor stage for each stage of the cascade.
In addition to these elements, the apparatus included gas passages connecting the various units and efforts were made to provide the most compact configuration of the structure within the constraints that the separating-nozzle units, coolers and the ducts connecting same were provided generally within the housing while the compressor and their associated parts were disposed externally of the housing.
The compressor had the role of displacing the gas mixture and forcing the same through the nozzles in jets with the lighter component diffusing outwardly bypassing the collecting opening or slit.
The coolers served to maintain a generally constant temperature in the region of the separating-nozzle units and ducts were provided for passing separated fractions in opposite directions in cascade to afford greater enrichment of at least one of the fractions in its specific isotope.
In the system of Ser. No. 928,436, the radial compressors were disposed outside the housing and below the latter with the separating-nozzle units having vertically arranged nozzles disposed above respective coolers. This system had the advantage that the compressors were readily accessible from the exterior and the pipe to and from the compressor could be relatively simple. The interior units, such as the separating-nozzle units, were readily accessible for maintenance and monitoring.
However, while this system was highly effective, it had the disadvantage that the apparatus occupied more space than was desirable. Furthermore, the gas passages to and from the compressor and even in the housing were relatively long so that thermodynamic disadvantages arose which reduced the efficiency.
Similar disadvantages characterize the system of the German patent document No. 25 42 296 and U.S. Pat. No. 4,093,436 in spite of the fact that the compressors were disposed within the housing in this arrangement.